Warren Buffet, chairman of Berkshire Hathaway, used "moat" to describe the advantage of barriers built by companies to defend the portfolios they offer. He said he wants "economic castles protected by unbreachable moats."

"A company that has a greater duration of competitive advantage is simply
worth more," said Morningstar chief equity strategist Paul Larson. "[Wide moat companies] should be able to parlay that into higher returns on invested capital.”

In 2007, Morningstar came up with the Wide Moat Focus Index, which is comprised of the 20 least expensive wide-moat stocks handpicked by the from 1,200 U.S. stocks. This index is used by the Market Vectors Morningstar Wide Moat Research ETF
and Elements Morningstar Wide Moat Focus.